In his new tell-all book, former New Jersey Gov. Jim McGreevey says he ruled out telling authorities a vengeful male ex-lover was allegedly blackmailing him for $50 million because it would have exposed his secret gay life.

“I knew it would stop the extortion campaign, but it would do nothing to protect my secret,” McGreevey writes in the “The Confession.”

“Once an official complaint was made, I knew my heterosexual pretense was over. My story would land in the pantheon of messy love affairs.”

In the book, a copy of which was obtained yesterday by The Associated Press, McGreevey describes his first passionate tryst with lover Golan Cipel in December 2001.

His wife, Dina, was in the hospital after giving birth to their daughter, Jacqueline, and state troopers were parked outside his Woodbridge, N.J., condominium.

McGreevey knew it was wrong, but “I was totally in love with this man.” He took Cipel by the hand and led him up to bed.

“We undressed and he kissed me. It was the first time in my life that a kiss meant what it was supposed to mean – it sent me through the roof,” the ex-governor writes.

“I was like a man emerging from 44 years in a cave to taste pure air for the first time, feel direct sunlight on pallid skin, warmth where there had only ever been a bone-chilling numbness.

“I pulled him to the bed and we made love like I’d always dreamed: a boastful, passionate, whispering, masculine kind of love,” McGreevey confesses.

“Afterward, I lay on the bed and watched Golan on the pillow next to me as he slept. At around 3 o’clock in the morning, I shook him out of bed for his walk home. When he was gone, I realized that this might all explode on me one day, but I just didn’t care. I felt invincible then.”

In 2002, Dina demanded that McGreevey tell her if he was gay.

“For a brief moment, I thought I could stop running that day,” he recalls. “But I didn’t have the nerve to tell my wife the truth. Instead, I said nothing.”

In the 384-page book, due in bookstores Tuesday, the ex-governor says the affair soured around Easter 2004 and Cipel, who insists he is straight, threatened to “take action” unless McGreevey agreed to see him.

On July 23, 2004, an aide told McGreevey that Cipel was threatening to file sexual-assault charges if he did not pony up $50 million.

Talks with Cipel’s lawyer went nowhere, McGreevey said, and the governor thought about going to federal authorities or quitting. In August 2004, he announced his resignation.

The ex-governor says that when he told his parents, “my father’s first response was, ‘You make a choice, Jim – Coke or Pepsi. You were married twice. You have two wonderful daughters. Why don’t you try to make that work?’ ”